On the heels of The National Parks: America’s Best Idea, filmmaker Ken Burns’ new six-part love letter, comes National Parks in Peril [PDF], a sobering report released on Thursday by the Natural Resources Defense Council (NRDC) and the Rocky Mountain Climate Organization (RMCO). The 25 most endangered parks are being threatened by dramatic declines in snow and water, by rising seas, extreme weather, the disappearance of native plants and wildlife, and by the onslaught of nonstop, human-generated pollution. The changes have already begun.

Warmer temperatures have killed as many as 90 percent of the pinon pines in Colorado’s Mesa Verde National Park. Grizzly bear birth rates are in decline in Yellowstone National Park along with the whitebark pine tree, which is being threatened by infestations of mountain pine beetle.

Zion National ParkPhoto: National Parks ServiceAccording to the report, “Climate change from human activity is the leading threat to wildlife, plants, water and ice in 25 of America ’s national parks.” From Denali in Alaska to the Florida Everglades, the 25 most at-risk parks span 22 states. Taken together, they represent many of America’s most majestic and wondrous natural landscapes.

The report warns that unless we can get our arms around the problem of climate change, namesake features will begin to vanish from our national parks – and soon. No more glaciers in Glacier National Park. No more Joshua trees in Joshua Tree National Monument. Some coastal parks – the Everglades and New York ’s Ellis Island are but two — will be completely submerged. And all of this could happen within the next 20 years.

Climate change “is the greatest threat that parks have ever faced,” said Stephen Saunders, President of the Rocky Mountain Climate Organization, former deputy director of the National Park Service and one of the report’s authors. “We’ve never lost a national park before, and for the first time we‘re in danger of losing one.”

National Parks In Peril offers 32 recommendations for saving America’s 331 parks. They include hastening “the development and deployment of clean technologies,” and urging National Park Service officials to “speak out publicly about how climate change and its impacts threaten national parks and the broader ecosystems on which they depend.”

At the press conference following the release of National Parks in Peril, the report’s sponsors were asked whether there is someone, anyone alive today who is advocating for the national parks as passionately and eloquently as John Muir, the legendary naturalist and writer who emerged as the star of Ken Burns’ new documentary series.

“There isn’t,” said Theo Spencer, senior advocate at the NRDC’s Climate Center. “John Muir and others helped prod congress and the president into creating these parks”.There was resistance at the time, from people who wanted to mine or log develop the land. But there were also leaders – former president Teddy Roosevelt among them – who recognized that preserving America’s scenic wonders for future generations was more important than financial gain.

“We seem to have lost sight of those kinds of priorities,” said Theo Spencer. “There hasn’t been a voice like John Muir. There hasn’t been a champion like Theodore Roosevelt. This really is a nonpartisan issue and it desperately needs the type of leadership that was shown at the time these parks were created.”

National Parks In Peril is an attempt to call attention to the dangers that threaten America’s parks and to rouse the leaders who can help save them.